1 files changed, 70 insertions, 0 deletions
diff --git a/src/content/navigates.js b/src/content/navigates.js
new file mode 100644
index 0000000..64e5fc0
--- /dev/null
+++ b/src/content/navigates.js
@@ -0,0 +1,70 @@
+const PREV_LINK_PATTERNS = [
+  /\bprev\b/i, /\bprevious\b/i, /\bback\b/i,
+  /</, /\u2039/, /\u2190/, /\xab/, /\u226a/, /<</
+];
+const NEXT_LINK_PATTERNS = [
+  /\bnext\b/i,
+  />/, /\u203a/, /\u2192/, /\xbb/, /\u226b/, />>/
+];
+
+const findLinkByPatterns = (win, patterns) => {
+  let links = win.document.getElementsByTagName('a');
+  return Array.prototype.find.call(links, (link) => {
+    return patterns.some(ptn => ptn.test(link.textContent));
+  });
+};
+
+const historyPrev = (win) => {
+  win.history.back();
+};
+
+const historyNext = (win) => {
+  win.history.forward();
+};
+
+const linkPrev = (win) => {
+  let link = win.document.querySelector('a[rel=prev]');
+  if (link) {
+    return link.click();
+  }
+  link = findLinkByPatterns(win, PREV_LINK_PATTERNS);
+  if (link) {
+    link.click();
+  }
+};
+
+const linkNext = (win) => {
+  let link = win.document.querySelector('a[rel=next]');
+  if (link) {
+    return link.click();
+  }
+  link = findLinkByPatterns(win, NEXT_LINK_PATTERNS);
+  if (link) {
+    link.click();
+  }
+};
+
+const parent = (win) => {
+  let loc = win.location;
+  if (loc.hash !== '') {
+    loc.hash = '';
+    return;
+  } else if (loc.search !== '') {
+    loc.search = '';
+    return;
+  }
+
+  const basenamePattern = /\/[^/]+$/;
+  const lastDirPattern = /\/[^/]+\/$/;
+  if (basenamePattern.test(loc.pathname)) {
+    loc.pathname = loc.pathname.replace(basenamePattern, '/');
+  } else if (lastDirPattern.test(loc.pathname)) {
+    loc.pathname = loc.pathname.replace(lastDirPattern, '/');
+  }
+};
+
+const root = (win) => {
+  win.location = win.location.origin;
+};
+
+export { historyPrev, historyNext, linkPrev, linkNext, parent, root };